Apparatus for drilling lateral bores deviating from vertical well bores



Feb. 12, 1952 J. A. ZUBLIN 2,585,207

APPARATUS FOR DRILLING LATERAL BORE-S DEVIATING FROM VERTICAL WELL BORES Filed Oct. 11, 1950 2 SHEETSSI*IEET l ATTORNEYS Feb. 12, 1952 J. A. ZUBLIN 2,585,207

APPARATUS FOR DRILLING LATERAL BORES DEVIATING FROM VERTICAL WELL BORES A) J ATTORNEYS Patented Feb. 12,1952

UNITED sjrnr s PTENT OFFICE APPARATUS FOR DRILLING LATERAL BORES DEVIATIN G FROM VERTICAL WELL BORES John A. Zublin, LosAngeles, Calif.

Application October 11, 1950, Serial No. 189,591

6 Claims. (01. 255-16) The present invention relates to novel apparatus for drilling lateral bores deviating from existing vertical well bores.

This application is a continuation-in-part of my application Serial No. 64,524, filed December 10, 1948.

It is a purpose and object of the invention to provide a combination unit susceptible of being assembled at the well surface and attached as a complete operative unit to the lower end of a conventional rotary drill string to be lowered into an existing well, oriented and operated to eflect drilling of a lateral bore by rotation of the conventional drill string pursuant to normal rotary drill practice.

More specifically, it is an object of ,the invention to provide a self-contained unit embodying a normally curved resilient flexible drill guide susceptible of being fiexed'to a lesser curvature, a flexible drill bit driving member disposed interiorly of the drill guide for free rotation therein and clutch means operative to permit free rotation of the drill bit while the flexible resilient normally curved drill uide is held against rotation by frictional engagement with the existing well bore and engageable to permit limited rotation of the curved resilient drill guide within the vertical well bore for purposes of orientation.

The art of drilling lateral bores deviating from an existing vertical well bore is not unknown and is the subject matter of several prior U. S. patents issued to me, examples being U. S. Patents Nos. 2,336,338, 2,344,277 and 2,382,933. The present invention is addressed to a specifically improved combination unit that is highly effective in the drilling of lateral bores from existing vertical well bores and which is especially well adapted for application to a conventional rotary drill string for operation through the medium of well-accepted rotary drilling practices.

A preferred embodiment of the invention is illustrated in the accompanying drawings in which Figure 1 is a side elevation of the combination unit of the invention showing the same in the position occupied thereby when inserted into a vertical well bore ready to initiate the drilling of a lateral bore. I

Figure 2 is a detailed cross-sectional view through the combination unit illustrating details of the clutching arrangement and showing the clutch elements disengaged.

Figure 3 is another detailed view similar to Figure 2 but illustrating the clutch elements in engaged position.

Figure 4 is a detailed view partially in cross section, showing the manner of attachment of the bit to the driving member, and the manner of mounting the flexible driving member within the resilient normally curved guide.

Referring to Figure 1, reference character Hi designates the lower end of the lowermost section of a conventional substantially non-resilient tubular drill string. It will be understood that the drill string is made up of numerous pipe sections usually approximately 30 feet in length and extends downwardly from the surface of the well. i

In Figure 1 the combination unit constituting thepresent invention is illustrated as being just introduced to the vertical well bore H. The combination unit embraces an upper flexible nonresilient tubular drill string section 12 which preferably takes the form of the non-resilient sectional flexiblemetallic drill pipe more particularly disclosed in my prior U. S. Patent 2,515,366 issued on July 18, 1950. Reference to that patent will indicate that the metallic sections which are interconnected by dovetailed slots are susceptible of relative limited axial movement permitting a substantial movement of the upper end of the flexible drill string section l2. It will be-understood that the combination unit of the present invention may, depending upon the length of the deviating bore to be drilled, embrace more than one section of non-resilient flexible pipe l2. The lower end of the flexible nonresillent drill string section l2 carries what for convenience is herein termeda sub 13. An impervious, preferably rubber, tubular liner M ex-' tends substantially from end to-end of the flexible drill string section l2 being secured in place therein by a combined threaded and riveted connection indicated at 15 in Figure 2. It will be understood that the upper end of the flexible tubular drill section :2 carries a complemental coupling member for attachment to the lower end of the lower section of the drill string l6 and that the upper end of the rubber tubular member [4 is attached to the upper end of the flexible drill string section 12 bya connection similar to that shown at I5 in Figure 2.

The sub l3 threadedly receives the upper end of the tubular coupling member 16. The lower end of the tubular coupling member I5 is threadedly secured to the upper end of a second flexible tubular bit driving member I? of somewhat less diameter than the flexible tubular drill string section l2 but otherwise of the same construction. The arrangement is such that the flexible tubular drill string section I2, the tubular cou drill string extending to the surface of the well.

No inner driving member is required.

Surrounding the tubular flexible drive member I1 and substantially coextensive in length therewith is the flexible resilient normally curved drill guide or deflector tube I9 which, when in the position shown in Figure 1, has been flexed to a considerably lesser curvature than that which it would assume under normally unstressed conditions. This normally curved flexible resilient drill guide I9 is preferably of the type disclosed in my prior U. S. Patent 2, 6 issued July 1950. This normally curved resilient drill guide is formed of tubular metal pipe having a slot through the wall thereof extending in a generally helical path along and around the pipe. The sides of the slot are provided with inter-meshing and inter-locking dovetailed teeth. The normally curved resilient drill guide I9 will be provided with a normal curvature in unstressed condition that approximates the curvature at which a deviating drain hole to be drilled thereby will assume.

By way of illustration, it is advantageous to employ flexible curved resilient drill guides such as I9 which have an over-all length of about 16 feet and a curvature in the unstressed condition that lies on a radius of about 16 feet. Under such conditions, the height of the are formed by the guide when in unstressed condition will be found to be about inches. When such a drillguide is inserted into a well bore, depending somewhat on the diameter of the well bore, the lower end of the drill guide will be forced against the side wall of the vertical bore under a pressure of the order of from 100 to 700 pounds.

The normally curved flexible drill guide I9 has no direct connection to the other elements of the combination unit of the present invention. In fact, the flexible non-resilient tubular drive mem ber I1 is mounted to rotate freely within the normally curved resilient flexible drill guide I9 in all permissible degrees of curvature thereof. To this end anti-friction bearings 20, 2I, 22 and 23 are interposed between the normally rotating elements of the unit and the normally non-rotating curved resilient drill guide I9.

Returning to the discussion of the manner'of attaching the bit I8 to the lower end of the flexible non-resilient tubular drive member II, it will be noted that the bit I9 is received in a tubular coupling member 24 which has a neck of reduced diameter 25 to the upper end of which the lower end of the flexible tubular drive member I! is threadedly secured. The lower end of the ,normally curved flexible resilient drill guide I9 .is threadedly connected to a short annular bearing member 26 which provides a seat for the antifriction bearing rollers 23 and which, at its lower end, is adapted to ride upon the ball bearings 21 which lie between the annular member 26 and the shoulder 28 of the coupling member 24 for the bit I8. A second set of ball bearings 29 lie between the upper end of the annular member -26 and the extreme lower end of the tubular flexible drive member IT. The arrangement is such that upon rotation of the tubular drive member I'I little or no rotational force is imparted to the normally curved flexible resilient drill guide I9. The tubular flexible drive member I'I, similarly to the tubular flexible drill string section I2, is provided with an impervious tubular liner, preferably of rubber, 30 secured at its opposite ends to the tubular flexible drive member I! through combined thread and rivet connections such as indicated at 3|, Figure 4.

Referring to Figure 2, it will be observed that the upper end of the normally curved resilient flexible drill guide I9 threadedly receives and carries a short annular bearing member 32 providing a seat for the anti-friction bearing rollers 29 and which is provided with a ball race 33 on which the ball bearings 34 ride. The tubular coupling-member I6 extends through the annular bearing member 32 and is free for axial movement therein. It will thus be seen that the normally curved resilient drill guide I9, together with the lower annular bearing member 26 and the upper annular bearing member 32 constitutes a unitary structure within which the tubular coupling member I6, the flexible tubular drive member I! and the reduced neck 25 of the bit coupling member 24 are adapted to freely rotate when the clutch means presently to be described is disengaged for drilling purposes.

Coming now to the clutch means of the combination unit which constitutes an important feature of the present invention, it will be observed that the annular bearing member 32 which as stated is integrally assembledwith the normally curved resilient drill guide I9 carries a semi-circular downwardly extending clutch tooth 35 and "that the upper end of the tubular flexible drive member I! carries a complemental semi-circular clutch tooth 36. The clutch teeth 35 and 36 are shown in disengaged position in Figure 2. In this position, the coupling member I6 and the inner flexible tubular drive member Il have been moved downwardly into and through the normally curved flexible resilient drill guide I9 which will be held against movement therewith by virtue of its frictional engagement with the side walls of an existing well bore. Thus, when the clutch elements 35 and 36 are in the position shown in Figure 2, rotation of the drill string, including the lower portion of the lower section If! thereof, together with the flexible drill string section I2, the coupling member I6 and the flexible drive member I'I, will cause positive rotation of the bit I8 when the latter is being forced against the side wall of the existing vertical well bore II due to the pressure imposed thereon through the flexing of the drill guide I9 to a lesser curvature than that normally to be assumed thereby.

It will be observed that a downward pull on the flexible resilient drill guide I9 will tend to move the clutch teeth 35 and 36 into engagement, i. e., toward the position illustrated in Figure 3. The weight of the flexible resilient drill guide I9 and its associated annular bearing members 25 and 32 has been found to be so great that in the absence of means affirmatively holding the clutch teeth 35 and 35 in disengaged position, there is a tendency for the clutch to close and thereby bring about unwanted rotation of the flexible normally curved resilient drill guide I9. To avoid this undesirable tendency of the clutch teeth to close, there is provided, pursuant to the present invention and as illustrated in Figures 2 and 3, .a

compression spring 31, theupper end of which bears, against'the annular member 32 and the lower end of which bears against a pressure ring 38 that rides on ball bearings 39 carried in a ball race 40 of an annularmember 4| fixedly secured to the flexible non-resilient drive member IT. The arrangement is such that the bearings 39 preclude transmission of the frictional resistance imposed by compression spring 3'! to the normally rotating flexible tubular drive member l1. It will be observed that the compression spring 31 is effective to force the annular member 32 and consequently the upper end of the flexible resilient drill guide I9 upwardly to thereby keep the clutch tooth 35 out of engagement with clutch tooth 36.

Now, assuming it is desired to orient the flexible normally curved resilient drill guide l9 so as to drill a lateral bore deviating from the vertical bore in a difierent azimuth, the drill string, including the lower portion ID of the lower section thereof will be raised at the surface of the well and this will elevate the tubular coupling member i6 and elongate the hollow sectional flexible drive member H with respect to the resilient normally curved guide l9 which, it is noted, will be held against substantial axial movement by frictional engagement with the well bore so as to efiect closing of the clutch and inter-engagement of the clutch teeth 35 and 36. It will be understood that during elevation of the drill string, slow partial rotation should be simultaneously effected to the end that clutch tooth 35 will be moved out of axial alignment with clutch tooth 36 and thereby permit their direct engagement. In Figure 3 the spring 31 is shown in its compressed condition which it assumes when the coupling member 16 moves upwardly elongating the hollow sectional drive member IT with respect to the curved resilient guide I9. It will be noted that the bearing member 32 carried at the upper end of the curved resilient drill guide [9 is provided with a sufllcient vertical extension to compensate for the required relative movement of member 32 and coupling member It to permit opening and closing of the clutch, i. e., engagement and disengagement of the clutch teeth 35 and 36 while retaining the ball bearings 34 in place.

In the operation of the combination unit conforming to the present invention, the upper end of the flexible non-resilient drill string section i2 is threaded onto the lower end ill of the lowermost section of a conventional rotary drill string.

The entire unit is lowered into the well into the zone of the producing formation where the drilling of a deviating bore is desired. The drill string is then slightly elevated to insure inter-engagement of the clutch teeth 35 and 36 and the drill string is then given a partial rotation requisite to impart desired orientation to the normally curved flexible drill guide 19. When the drill guide H! has been appropriately oriented, the drill string is again lowered, the lowering of the drill string being sufiicient to insure disengagement of the clutch teeth 35 and 36, whereupon rotation of the drill string is commenced, which effects a positive drive of the bit l8 which, under the pressure imposed due to the flexing of the curved resilient drill guide 19 initiates and continues to drill a lateral bore deviating from the existing vertical well bore.

While I have illustrated the interpositioning of anti-friction bearings to the flexible non-resilient driving member I! and the flexible resilient normally; curved drilliguide l 9, it isxto be understood thatwhere drilling is effected through the employment of anoil or other lubricatingbase medium as the circulating drilling fluid, the parts of the assembly embraced by the present invention will be self-lubricated and friction thereby minimized. to-such an extent that the anti-friction means maybe dispensed with. Thus, while employment of anti-friction means isillustrated inthe exemplified embodiment, the inclusion of such illustration isnot to be regarded as a limitation upon the invention. i 1."

Having thus described my invention, what I claimis; i t :.1 4 1.

1. In apparatus for drilling a lateral bore deviating from an existing vertical well bore, a resilient, normally curved, tubular drill guide which must be forcibly flexed from its normally curved configuration to enter an existing well bore, the resiliency of said drill guide when so flexed being adequate to store suflicientpotential energy to forcibly guide a rotating drill bit in a path to drill a lateral bore deviating from the existing vertical well bore, a flexible, non-resilient, bit driving member extending through and rotatable within said drill guide, a flexible, non-resilientdrill string section secured to the upper end of said flexible bit driving member, said drill string section and said bit driving member each comprising a plurality of generally tubular rigid elements interconnected in end to end relationship for relative angular movement with adjacent ele ments having longitudinally extending intermeshing teeth thereon for transmitting torque from element to element thereof, a drill bit secured to the lower end of said bit driving memher for rotation therewith, and means for securing the upper end of said drill string section to the lower end of a rigid rotary drill string for rotation in unison therewith.

2. Apparatus as defined in claim 1 having means for effecting angular orientation of said normally curved tubular drill guide, said orienting means comprising a clutch operative, when engaged, to cause said normally curved drill guide to rotate with said flexible drill string section and said flexible bit driving member.

3. Apparatus as defined in claim 1 having means for effecting angular orientation of said normally curved tubular drill guide, said orienting means comprising a clutch, and a spring member biasing said clutch toward disengaged condition, said clutch being operative, when engaged, to cause said normally curved drill guide to rotate with said flexible drill string section and said flexible bit driving member.

4. Apparatus for drilling a curved bore deflecting from an existing bore, said apparatus comprising a normally curved, flexible, resilient, deflector tube, a drilling bit rotatably mounted at the lower end of said deflector tube, a flexible drive member rotatable within said deflector tube and having its lower end connected to said drilling bit to rotate the same upon rotation of said drive member, said drive member comprising a plurality of tubular sections joined at their ends by loosely intermeshing and interlocking teeth thus permitting variations in the length of said drive member, means for securing a drill pipe to the upper end of said drive member, and a clutch between said drive member and said deflector tube operable. when engaged, to cause said deflector tube to rotate during rotation of said drive member, said clutch being arranged to engage upon elongation of said drive member as a result of upward movement of said drill pipe relative to -said deflector pipe and to disengage upon shorten-- ing of said drive member as a result of downward movement of said drill pipe relative to said deflector pipe. 5. ,Apparatus as defined in claim 4 in which a flexible hose extends through the interior of said drive member for conveying mud from a drill pipe to said drilling bit. e

6. Apparatus as defined in claim. 4 in which said clutch is a toothed clutch'comprising a single downwardly extending tooth secured to said deflector pipe and a single upwardly extending tooth secured to said drive member, said teeth REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,336,338 Zublin Dec. 7, 1943 2,344,277 Zublin Mar. 14, 1944 

